Sampling circuit, buck-boost converter and energy storage system

Abstract

The invention provides a sampling circuit, a buck-boost converter and an energy storage system, and the sampling circuit comprises a first sampling unit which is connected to a buck unit and is used for collecting a first current of the buck unit; the second sampling unit is connected to the boosting unit and is used for acquiring a second current of the boosting unit; the controller is connected to the first sampling unit, the second sampling unit and the direct-current power supply; wherein the controller is used for controlling the output power of the direct-current power supply according to the first current when the input voltage of the buck-boost converter is greater than or equal to the output voltage, and controlling the output power of the direct-current power supply according to the second current when the input voltage of the buck-boost converter is less than the output voltage. The sampling circuit provided by the invention can reduce the cost and ensure the sampling precision.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage devices, and in particular to a sampling circuit, a buck-boost converter and an energy storage system. Background Art

[0002] In the related technology, during the operation of the photovoltaic energy storage system, it is necessary to sample the current in the circuit, and then adjust the operating power of the photovoltaic energy storage system according to the sampled current to ensure that the power of the electric energy output by the photovoltaic energy storage system is maximized, thereby ensuring the operating efficiency of the photovoltaic energy storage system. Usually, during the operation of the photovoltaic energy storage system, Hall components or high-precision resistors are usually used for current sampling. Among them, the Hall component sampling method is relatively expensive, and the high-precision resistor sampling is divided into high-end resistor sampling and low-end resistor sampling. The high-end resistor sampling method requires the addition of an isolated power supply, which has a complex structure. The low-end resistor sampling has the problem of parallel common ground current sharing, which leads to inaccurate sampling results. Summary of the invention

[0003] The present invention aims to at least solve the technical problems in the prior art of high cost and poor accuracy of sampling circuits of photovoltaic energy storage systems.

[0004] To this end, a first aspect of the present invention provides a sampling circuit.

[0005] A second aspect of the present invention provides a buck-boost converter.

[0006] A third aspect of the present invention provides an energy storage system.

[0007] A first aspect of the present invention provides a sampling circuit for a buck-boost converter, wherein the input end of the buck-boost converter is connected to a DC power supply, the buck-boost converter includes a buck unit and a boost unit, and the sampling circuit includes: a first sampling unit, connected to the buck unit, for collecting a first current of the buck unit; a second sampling unit, connected to the boost unit, for collecting a second current of the boost unit; a controller, connected to the first sampling unit, the second sampling unit and the DC power supply; wherein the controller is used to control the output power of the DC power supply according to the first current when the input voltage of the buck-boost converter is greater than or equal to the output voltage, and to control the output power of the DC power supply according to the second current when the input voltage of the buck-boost converter is less than the output voltage.

[0008] The sampling circuit provided by the present invention can be used in a buck-boost converter, wherein the input end of the buck-boost converter is connected to a DC power supply, and the output end of the buck-boost converter can be used to connect to a load, thereby supplying power to the load. Specifically, the DC power supply can be a photovoltaic panel, through which light energy can be converted into DC power to supply power to the load.

[0009] Specifically, the buck-boost converter may include a buck unit and a boost unit. During the operation of the buck-boost converter, the DC power provided by the DC power supply may be bucked by the buck unit, thereby reducing the voltage of the DC power provided by the DC power supply. Alternatively, the DC power provided by the DC power supply may be boosted by the boost unit, thereby increasing the voltage of the DC power provided by the DC power supply. That is, the buck-boost converter may operate in a buck mode or in a boost mode.

[0010] Further, the sampling circuit includes a first sampling unit and a second sampling unit, wherein the first sampling unit is connected to the buck unit, so that when the DC power supply is in the buck mode, the first current of the buck unit is sampled. Correspondingly, the second sampling unit is connected to the boost unit, so that when the DC power supply is in the boost mode, the second current of the boost unit is sampled.

[0011] Furthermore, the sampling circuit also includes a controller, which is respectively connected to the first sampling unit, the second sampling unit and the DC power supply. During the operation of the buck-boost converter, the controller can first determine the relationship between the input voltage and the output voltage of the buck-boost converter. When the input voltage of the buck-boost converter is greater than or equal to the output voltage, it can be determined that the buck-boost converter is in the buck mode. At this time, the controller can control the output power of the DC power supply according to the first current of the buck unit collected by the first sampling unit, to ensure that the power output to the load by the buck-boost converter is the same as the power output by the DC power supply, thereby ensuring the operating efficiency of the DC power supply.

[0012] On the contrary, when the input voltage of the buck-boost converter is lower than the output voltage, it can be determined that the buck-boost converter is operating in boost mode. At this time, the controller can control the output power of the DC power supply according to the second current of the boost unit collected by the second sampling unit, to ensure that the power output to the load by the buck-boost converter is the same as the power output by the DC power supply, thereby ensuring the operating efficiency of the DC power supply.

[0013] Specifically, the controller can calculate the output current of the buck-boost converter based on the first current or the second circuit, and then control the output power of the DC power supply based on the output current of the buck-boost converter to ensure that the power output to the load by the buck-boost converter is the same as the power output by the DC power supply, thereby ensuring the operating efficiency of the DC power supply.

[0014] The sampling circuit provided by the present application can collect the first current of the buck unit and the second current of the boost unit respectively when the buck-boost converter is in the buck mode and the boost mode by setting the first sampling unit and the second sampling unit. Furthermore, the output power of the DC power supply is controlled according to the first current and the second current respectively by using the software analysis and algorithm of the controller. Compared with the sampling method using Hall components in the related art, it can reduce the cost of the sampling circuit, avoid the problem of power supply loss, and improve the sampling accuracy. Compared with the high-end resistor sampling method, there is no need to set an isolated power supply, which can simplify the structure of the sampling circuit and reduce the loss. Compared with the low-end resistor sampling method, there is no problem of parallel common ground current sharing, which can improve the sampling accuracy.

[0015] In addition, the sampling circuit in the above technical solution provided by the present invention may also have the following additional technical features:

[0016] In some technical schemes, optionally, the first sampling unit includes: a first resistor, one end of the first resistor is connected to the boost unit, and the other end of the first resistor is grounded; a first operational amplifier, the input end of the first operational amplifier is connected to the two ends of the first resistor, and the output end of the first operational amplifier is connected to the controller; wherein the first operational amplifier is used to collect the voltage across the first resistor and determine the first current based on the voltage across the first resistor.

[0017] In some technical schemes, optionally, the second sampling unit includes: a second resistor, one end of the second resistor is connected to the boost unit, and the other end of the second resistor is grounded; a second operational amplifier, the input end of the second operational amplifier is connected to the two ends of the second resistor, and the output end of the second operational amplifier is connected to the controller; wherein the second operational amplifier is used to collect the voltage across the second resistor and determine the second current based on the voltage across the second resistor.

[0018] A second aspect of the present invention provides a buck-boost converter, comprising a sampling circuit as described in any one of the above technical solutions.

[0019] The buck-boost converter provided by the present invention includes the sampling circuit of any one of the above technical solutions, so the buck-boost converter includes all the beneficial effects of the sampling circuit, which will not be repeated here.

[0020] In some technical solutions, optionally, the buck-boost converter also includes: an energy storage inductor, a first end of the energy storage inductor is connected to a DC power supply; a buck unit, one end of the buck unit is connected to the first end of the energy storage inductor, and the other end of the buck unit is grounded; wherein the first sampling unit is connected to the buck unit; a boost unit, one end of the boost unit is connected to the second end of the energy storage inductor, and the other end of the boost unit is grounded; wherein the second sampling unit is connected to the boost unit.

[0021] In some technical solutions, optionally, the step-down unit includes: a first switch element, a first end of the first switch element is connected to a DC power supply, and a second end of the first switch element is connected to a first end of an energy storage inductor; a first diode, a cathode of the first diode is connected to the second end of the first switch element, and an anode of the first diode is connected to one end of a first resistor of the first sampling unit.

[0022] In some technical solutions, optionally, the buck-boost converter further includes: a first capacitor, one end of the first capacitor is connected to the first end of the first switch element, and the other end of the first capacitor is grounded.

[0023] In some technical solutions, optionally, the boost unit includes: a second switch element, a first end of the second switch element is connected to the second end of the energy storage inductor, and a second end of the second switch element is connected to one end of the second resistor of the second sampling unit; and a second diode, a positive electrode of the second diode is connected to the first end of the second switch element.

[0024] In some technical solutions, optionally, the buck-boost converter further includes: a second capacitor, one end of the second capacitor is connected to the cathode of the second diode, and the other end of the second capacitor is grounded.

[0025] A second aspect of the present invention provides an energy storage system, comprising: a DC power supply, such as a buck-boost converter in any one of the above technical solutions, wherein the input end of the buck-boost converter is connected to the DC power supply.

[0026] The energy storage system provided by the present invention includes the buck-boost converter of any one of the above technical solutions, so the energy storage system includes all the beneficial effects of the buck-boost converter, which will not be repeated here.

[0027] Furthermore, the energy storage system may include a photovoltaic energy storage system, that is, the DC power supply of the energy storage system may be a photovoltaic panel, through which light energy may be converted into DC power to supply power to the load.

[0028] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0030] Figure 1 A circuit diagram of an energy storage system according to an embodiment of the present invention is shown;

[0031] Figure 2 The waveform diagram of the output current during the operation of the buck-boost converter according to the embodiment of the present invention is shown.

[0032] in, Figure 1 The corresponding relationship between the reference numerals and the component names is as follows:

[0033] 100 sampling circuit, 102 first sampling unit, 104 second sampling unit, 106 controller, 108 first resistor, 110 first operational amplifier, 112 second resistor, 114 second operational amplifier, 200 buck-boost converter, 202 buck unit, 204 boost unit, 206 energy storage inductor, 208 first switch, 210 first diode, 212 first capacitor, 214 second switch, 216 second diode, 218 second capacitor, 300 energy storage system, 302 DC power supply. DETAILED DESCRIPTION

[0034] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0036] Refer to the following Figure 1 and Figure 2 The sampling circuit, buck-boost converter and energy storage system provided according to some embodiments of the present invention are described.

[0037] Some embodiments of the present invention provide a sampling circuit 100, such as Figure 1 As shown, the sampling circuit 100 is used for a buck-boost converter 200, wherein the input end of the buck-boost converter 200 is connected to a DC power supply 302, the buck-boost converter 200 includes a buck unit 202 and a boost unit 204, and the sampling circuit 100 includes: a first sampling unit 102, connected to the buck unit 202, for collecting a first current of the buck unit 202; a second sampling unit 104, connected to the boost unit 204, for collecting a second current of the boost unit 204; a controller 106, connected to the first sampling unit 102, the second sampling unit 104 and the DC power supply 302; wherein the controller 106 is used to control the output power of the DC power supply 302 according to the first current when the input voltage of the buck-boost converter 200 is greater than or equal to the output voltage, and to control the output power of the DC power supply 302 according to the second current when the input voltage of the buck-boost converter 200 is less than the output voltage.

[0038] The sampling circuit 100 provided by the present invention can be used in a buck-boost converter 200, wherein the input end of the buck-boost converter 200 is connected to a DC power supply 302, and the output end of the buck-boost converter 200 can be used to connect to a load, thereby supplying power to the load. Specifically, the DC power supply 302 can be a photovoltaic panel, through which light energy can be converted into DC power to supply power to the load.

[0039] Specifically, the buck-boost converter 200 may include a buck unit 202 and a boost unit 204. During the operation of the buck-boost converter 200, the DC power provided by the DC power source 302 may be bucked by the buck unit 202, thereby reducing the voltage of the DC power provided by the DC power source 302. Alternatively, the DC power provided by the DC power source 302 may be boosted by the boost unit 204, thereby increasing the voltage of the DC power provided by the DC power source 302. That is, the buck-boost converter 200 may operate in a buck mode or in a boost mode.

[0040] Further, the sampling circuit 100 includes a first sampling unit 102 and a second sampling unit 104, wherein the first sampling unit 102 is connected to the buck unit 202, so as to sample the first current of the buck unit 202 when the DC power supply 302 is in the buck mode. Correspondingly, the second sampling unit 104 is connected to the boost unit 204, so as to sample the second current of the boost unit 204 when the DC power supply 302 is in the boost mode.

[0041] Furthermore, the sampling circuit 100 also includes a controller 106, which is connected to the first sampling unit 102, the second sampling unit 104 and the DC power supply 302 respectively. During the operation of the buck-boost converter 200, the controller 106 can first determine the magnitude relationship between the input voltage and the output voltage of the buck-boost converter 200. When the input voltage of the buck-boost converter 200 is greater than or equal to the output voltage, it can be determined that the buck-boost converter 200 is in the buck mode. At this time, the controller 106 can control the output power of the DC power supply 302 according to the first current of the buck unit 202 collected by the first sampling unit 102, to ensure that the power output to the load by the buck-boost converter 200 is the same as the power output by the DC power supply 302, thereby ensuring the operation efficiency of the DC power supply 302.

[0042] On the contrary, when the input voltage of the buck-boost converter 200 is lower than the output voltage, it can be determined that the buck-boost converter 200 is operating in the boost mode. At this time, the controller 106 can control the output power of the DC power supply 302 according to the second current of the boost unit 204 collected by the second sampling unit 104, to ensure that the power output to the load by the buck-boost converter 200 is the same as the power output by the DC power supply 302, thereby ensuring the operating efficiency of the DC power supply 302.

[0043] The sampling circuit 100 provided in the present application can collect the first current of the buck unit 202 and the second current of the boost unit 204 respectively when the buck-boost converter 200 is in the buck mode and the boost mode by setting the first sampling unit 102 and the second sampling unit 104. Further, the output power of the DC power supply 302 is controlled according to the first current and the second current respectively by using the software analysis and algorithm of the controller 106. Compared with the sampling method using Hall elements in the related art, the cost of the sampling circuit 100 can be reduced, and there will be no problem of power supply loss, which can improve the sampling accuracy. Compared with the high-end resistor sampling method, there is no need to set an isolated power supply, which can simplify the structure of the sampling circuit 100 and reduce the loss. Compared with the low-end resistor sampling method, there will be no problem of parallel common ground current sharing, which can improve the sampling accuracy.

[0044] In some embodiments, optionally, the first sampling unit 102 includes: a first resistor 108, one end of the first resistor 108 is connected to the step-down unit 202, and the other end of the first resistor 108 is grounded; a first operational amplifier 110, an input end of the first operational amplifier 110 is connected to both ends of the first resistor 108, and an output end of the first operational amplifier 110 is connected to the controller 106; wherein the first operational amplifier 110 is used to collect the voltage across the first resistor 108, and determine the first current according to the voltage across the first resistor 108.

[0045] In this embodiment, the first sampling unit 102 may include a first resistor 108 and a first operational amplifier 110. By connecting the first resistor 108 to the buck unit 202, during the operation of the buck-boost converter 200, the current in the buck unit 202 flows through the first resistor 108, so that the current in the first resistor 108 can be sampled to achieve sampling of the first current of the buck unit 202.

[0046] Specifically, by setting the first operational amplifier 110, the two input terminals of the first operational amplifier 110 are connected to the two ends of the first resistor 108, so that the voltage across the first resistor 108 is collected, and the collected voltage is amplified, and then the current flowing through the first resistor 108 can be determined according to the voltage across the first resistor 108 and the resistance value of the first resistor 108, that is, the first current of the step-down unit 202 is determined, and then the sampling process of the first current of the step-down unit 202 is realized.

[0047] Furthermore, the output end of the first operational amplifier 110 is connected to the controller 106, so that the controller 106 can determine the first current of the buck unit 202 based on the amplified voltage across the first resistor 108 and the resistance value of the first resistor 108, thereby realizing the sampling process of the first current of the buck unit 202.

[0048] That is, the first sampling unit 102 can sample the first current of the buck unit 202 through the first resistor 108 in cooperation with the software analysis and algorithm of the controller 106 , thereby reducing the cost of the sampling circuit 100 and ensuring sampling accuracy.

[0049] In some embodiments, optionally, the second sampling unit 104 includes: a second resistor 112, one end of the second resistor 112 is connected to the boost unit 204, and the other end of the second resistor 112 is grounded; a second operational amplifier 114, the input end of the second operational amplifier 114 is connected to the two ends of the second resistor 112, and the output end of the second operational amplifier 114 is connected to the controller 106; wherein the second operational amplifier 114 is used to collect the voltage across the second resistor 112, and determine the second current according to the voltage across the second resistor 112.

[0050] In this embodiment, the second sampling unit 104 may include a second resistor 112 and a second operational amplifier 114. By connecting the second resistor 112 to the boost unit 204, during the operation of the buck-boost converter 200, the current in the boost unit 204 flows through the second resistor 112, so that the current in the second resistor 112 can be sampled to achieve sampling of the second current of the boost unit 204.

[0051] Specifically, by setting a second operational amplifier 114, the two input terminals of the second operational amplifier 114 are connected to the two ends of the second resistor 112, so that the voltage across the second resistor 112 is collected, and the collected voltage is amplified, and then the current flowing through the second resistor 112 can be determined according to the voltage across the second resistor 112 and the resistance value of the second resistor 112, that is, the second current of the boost unit 204 is determined, and then the sampling process of the second current of the boost unit 204 is realized.

[0052] Furthermore, the output end of the second operational amplifier 114 is connected to the controller 106, so that the controller 106 can determine the second current of the boost unit 204 based on the amplified voltage across the second resistor 112 and the resistance value of the second resistor 112, thereby realizing the sampling process of the second current of the boost unit 204.

[0053] That is, the second sampling unit 104 can sample the second current of the boost unit 204 through the second resistor 112 in cooperation with the software analysis and algorithm of the controller 106 , thereby reducing the cost of the sampling circuit 100 and ensuring sampling accuracy.

[0054] Some embodiments of the present invention provide a buck-boost converter 200 , comprising the sampling circuit 100 as described in any one of the above embodiments.

[0055] The buck-boost converter 200 provided by the present invention includes the sampling circuit 100 of any one of the above embodiments. Therefore, the buck-boost converter 200 includes all the beneficial effects of the sampling circuit 100, which will not be described in detail here.

[0056] In some embodiments, optionally, the buck-boost converter 200 includes: an energy storage inductor 206, a first end of the energy storage inductor 206 is connected to the DC power supply 302; a buck unit 202, one end of the buck unit 202 is connected to the first end of the energy storage inductor 206, and the other end of the buck unit 202 is grounded; wherein the first sampling unit 102 is connected to the buck unit 202; a boost unit 204, one end of the boost unit 204 is connected to the second end of the energy storage inductor 206, and the other end of the boost unit 204 is grounded; wherein the second sampling unit 104 is connected to the boost unit 204.

[0057] In this embodiment, the buck-boost converter 200 may include an energy storage inductor 206, a buck unit 202, and a boost unit 204, wherein the first end of the energy storage inductor 206 is connected to the DC power supply 302, and the energy storage inductor 206 can be used to store and release the electric energy provided by the DC power supply 302 during the operation of the buck-boost converter 200, and cooperate with the buck unit 202 and the boost unit 204 to reduce or increase the voltage value of the electric energy provided by the DC power supply 302, so as to provide appropriate electric energy for the load. That is, the buck-boost converter 200 can operate in a buck mode or in a boost mode.

[0058] Furthermore, the first sampling unit 102 of the sampling circuit 100 is connected to the buck unit 202. During the operation of the buck-boost converter 200, the controller 106 can first determine the magnitude relationship between the input voltage and the output voltage of the buck-boost converter 200. When the input voltage of the buck-boost converter 200 is greater than or equal to the output voltage, it can be determined that the buck-boost converter 200 is in the buck mode. At this time, the controller 106 can control the output power of the DC power supply 302 according to the first current of the buck unit 202 collected by the first sampling unit 102, to ensure that the power output to the load by the buck-boost converter 200 is the same as the power output by the DC power supply 302, thereby ensuring the operating efficiency of the DC power supply 302.

[0059] Furthermore, the second sampling unit 104 of the sampling circuit 100 is connected to the boost unit 204. When the input voltage of the buck-boost converter 200 is less than the output voltage, it can be determined that the buck-boost converter 200 is in the boost mode. At this time, the controller 106 can control the output power of the DC power supply 302 according to the second current of the boost unit 204 collected by the second sampling unit 104, to ensure that the power output to the load by the buck-boost converter 200 is the same as the power output by the DC power supply 302, thereby ensuring the operating efficiency of the DC power supply 302.

[0060] In some embodiments, optionally, the step-down unit 202 includes: a first switch 208, a first end of the first switch 208 is connected to the DC power supply 302, and a second end of the first switch 208 is connected to the first end of the energy storage inductor 206; a first diode 210, a cathode of the first diode 210 is connected to the second end of the first switch 208, and an anode of the first diode 210 is connected to one end of the first resistor 108 of the first sampling unit 102.

[0061] In this embodiment, the step-down unit 202 includes a first switch 208 and a first diode 210, wherein a first end of the first switch 208 is connected to the DC power supply 302, a second end of the first switch 208 is connected to a first end of the energy storage inductor 206, a cathode of the first diode 210 is connected to the second end of the first switch 208, and an anode of the first diode 210 is connected to one end of the first resistor 108 of the first sampling unit 102.

[0062] During the operation of the buck-boost converter 200, when the input voltage of the buck-boost converter 200 is greater than or equal to the output voltage, the buck-boost converter 200 is in the buck mode. At this time, the first switch 208 is switched on and off at a preset frequency. When the first switch 208 is turned on, the first diode 210 is turned off, and the current flows to the load through the energy storage inductor 206. The energy storage inductor 206 has self-inductance, which hinders the rise of the current, so that the output voltage of the buck-boost converter 200 is lower than the input voltage, and the electric energy is converted into magnetic energy for storage. When the first switch 208 is turned off, the energy storage inductor 206 is discharged, so that the first diode 210 is turned on, and the electric energy stored in the energy storage inductor 206 is transmitted to the load to realize power supply to the load.

[0063] At the same time, during the operation of the buck unit 202, the first current of the buck unit 202 is sampled through the first resistor 108 of the first sampling unit 102. The controller 106 of the sampling circuit 100 can determine the output current of the buck-boost converter 200 at this time based on the first current. Specifically, the output current of the buck-boost converter 200 at this time is the current flowing through the first resistor 108.

[0064] In some embodiments, optionally, the buck-boost converter 200 further includes: a first capacitor 212 , one end of the first capacitor 212 is connected to the first end of the first switch 208 , and the other end of the first capacitor 212 is grounded.

[0065] In this embodiment, the buck-boost converter 200 may further include a first capacitor 212, one end of the first capacitor 212 is connected to the first end of the first switch 208, and the other end of the first capacitor 212 is grounded. By providing the first capacitor 212, it is possible to filter the electric energy input to the buck-boost converter 200, thereby reducing the pulsation of the current, avoiding the influence of the current pulsation on the operation process of the buck-boost converter 200, and ensuring the stability of the buck-boost converter 200 during operation.

[0066] In some embodiments, optionally, the boost unit 204 includes: a second switch element 214, a first end of the second switch element 214 is connected to the second end of the energy storage inductor 206, and a second end of the second switch element 214 is connected to one end of the second resistor 112 of the second sampling unit 104; and a second diode 216, a positive electrode of the second diode 216 is connected to the first end of the second switch element 214.

[0067] In this embodiment, the boost unit 204 includes a second switch 214 and a second diode 216, wherein a first end of the second switch 214 is connected to a second end of the energy storage inductor 206, a second end of the second switch 214 is connected to one end of the second resistor 112 of the second sampling unit 104, an anode of the second diode 216 is connected to a first end of the second switch 214, and a cathode of the second diode 216 is used to be connected to a load.

[0068] During the operation of the buck-boost converter 200, when the input voltage of the buck-boost converter 200 is less than the output voltage, the power supply point is in the boost mode. At this time, the second switch 214 is switched on and off at a preset frequency. When the second switch 214 is turned on, the current in the energy storage inductor 206 increases linearly, and the second diode 216 is turned on, thereby supplying power to the load. When the second switch 214 is turned off, the current in the energy storage inductor 206 gradually decreases, and the second switch 214 remains in the on state. At this time, the output voltage of the buck-boost converter 200 is equal to the sum of the input voltage of the buck-boost converter 200 and the voltage across the energy storage inductor 206, thereby realizing the boost mode of the buck-boost converter 200.

[0069] At the same time, during the operation of the boost unit 204, the second current of the boost unit 204 is sampled through the second resistor 112 of the second sampling unit 104. The controller 106 of the sampling circuit 100 can determine the output current of the boost-buck converter 200 at this time based on the second current. Specifically, the output current Io of the boost-buck converter 200 at this time is I_adc1×(1-D), wherein Io is the output current of the boost-buck converter 200, I_adc1 is the second current of the second resistor 112, and D is the duty cycle of the second switch 214 during the on-off process.

[0070] In addition, it should be noted that, when the buck-boost converter 200 is in the boost mode, the first switch 208 remains in the on state to ensure that the electric energy of the DC power source 302 can continue to flow to the energy storage inductor 206 .

[0071] Specifically, Figure 2As shown, during the operation of the buck-boost converter 200, the sampling circuit 100 is only allowed to collect current information once in each operation cycle of the buck-boost converter 200, and the current collection time point is usually at the midpoint between the maximum value of the inductor current of the energy storage inductor 206 and the minimum value of the inductor current of the energy storage inductor 206. Wherein, when the buck-boost converter 200 is in the buck mode, the time when the current flows through the first resistor 108 is from t1 to t2, and the current collection time point is the midpoint of the current falling process, that is, the position of point b in the figure. When the buck-boost converter 200 is in the boost mode, the time when the current flows through the second resistor 112 is from 0 to t1, and the current collection time point is the midpoint of the current rising process, that is, the position of point a in the figure.

[0072] In some embodiments, optionally, the buck-boost converter 200 further includes: a second capacitor 218 , one end of the second capacitor 218 is connected to the cathode of the second diode 216 , and the other end of the second capacitor 218 is grounded.

[0073] In this embodiment, the cathode of the second diode 216 is also connected to the second capacitor 218, that is, one end of the second capacitor 218 is connected to the cathode of the second diode 216, and the other end of the second capacitor 218 is grounded. By providing the second capacitor 218, the current output by the buck-boost converter 200 can be filtered, thereby reducing the pulsation of the output current of the buck-boost converter 200, avoiding the influence of the current pulsation on the load operation process, and ensuring the stable operation of the load.

[0074] Some embodiments of the present invention further provide an energy storage system 300 , comprising: a DC power supply 302 , such as the buck-boost converter 200 of any of the above embodiments, wherein the input end of the buck-boost converter 200 is connected to the DC power supply 302 .

[0075] The energy storage system 300 provided in the embodiment of the present invention includes the buck-boost converter 200 of any one of the above embodiments. Therefore, the energy storage system 300 includes all the beneficial effects of the buck-boost converter 200, which will not be repeated here.

[0076] Furthermore, the energy storage system 300 may include a photovoltaic energy storage system, that is, the DC power supply 302 of the energy storage system 300 may be a photovoltaic panel, through which light energy may be converted into DC power to supply power to the load.

[0077] In the description of the present invention, the term "plurality" refers to two or more than two. Unless otherwise clearly defined, the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention. The terms "connection", "installation", "fixation", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sampling circuit for a buck-boost converter, characterized in that: The input end of the buck-boost converter is connected to a DC power supply, the buck-boost converter includes a buck unit and a boost unit, and the sampling circuit includes: A first sampling unit, connected to the step-down unit, and configured to collect a first current of the step-down unit; A second sampling unit, connected to the boost unit, for collecting a second current of the boost unit; a controller connected to the first sampling unit, the second sampling unit and the DC power supply; In which, the controller is used to control the output power of the DC power supply according to the first current when the input voltage of the buck-boost converter is greater than or equal to the output voltage, and to control the output power of the DC power supply according to the second current when the input voltage of the buck-boost converter is less than the output voltage.

2. The sampling circuit according to claim 1, characterized in that: The first sampling unit comprises: A first resistor, one end of the first resistor is connected to the voltage reduction unit, and the other end of the first resistor is grounded; A first operational amplifier, wherein an input end of the first operational amplifier is connected to two ends of the first resistor, and an output end of the first operational amplifier is connected to the controller; The first operational amplifier is used to collect the voltage across the first resistor and determine the first current according to the voltage across the first resistor.

3. The sampling circuit according to claim 1, characterized in that: The second sampling unit comprises: A second resistor, one end of the second resistor is connected to the boost unit, and the other end of the second resistor is grounded; a second operational amplifier, wherein an input terminal of the second operational amplifier is connected to two ends of the second resistor, and an output terminal of the second operational amplifier is connected to the controller; The second operational amplifier is used to collect the voltage across the second resistor and determine the second current according to the voltage across the second resistor.

4. A buck-boost converter, characterized in that: include: The sampling circuit according to any one of claims 1 to 3.

5. The buck-boost converter according to claim 4, characterized in that: Also includes: An energy storage inductor, wherein a first end of the energy storage inductor is connected to a DC power supply; A step-down unit, one end of which is connected to the first end of the energy storage inductor, and the other end of which is grounded; Wherein, the first sampling unit is connected to the voltage reduction unit; A boost unit, one end of which is connected to the second end of the energy storage inductor, and the other end of which is grounded; Wherein, the second sampling unit is connected to the boost unit.

6. The buck-boost converter according to claim 5, characterized in that: The step-down unit comprises: a first switch element, wherein a first end of the first switch element is connected to the DC power supply, and a second end of the first switch element is connected to a first end of the energy storage inductor; A first diode, wherein a cathode of the first diode is connected to the second end of the first switch element, and an anode of the first diode is connected to one end of the first resistor of the first sampling unit.

7. The buck-boost converter according to claim 6, characterized in that: Also includes: A first capacitor, one end of the first capacitor is connected to the first end of the first switch element, and the other end of the first capacitor is grounded.

8. The buck-boost converter according to claim 5, characterized in that: The boost unit comprises: a second switch element, wherein a first end of the second switch element is connected to a second end of the energy storage inductor, and a second end of the second switch element is connected to one end of a second resistor of the second sampling unit; A second diode, an anode of the second diode is connected to the first end of the second switch element.

9. The buck-boost converter according to claim 8, characterized in that: Also includes: A second capacitor, one end of the second capacitor is connected to the cathode of the second diode, and the other end of the second capacitor is grounded.

10. An energy storage system, characterized in that: include: DC power supply; The buck-boost converter according to any one of claims 4 to 9, wherein the input end of the buck-boost converter is connected to the DC power supply.

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